1. Field of the Invention
The present invention relates to a touch screen, a touch panel, and a display device equipped therewith.
2. Description of the Background Art
A touch panel detecting a touch by a pointing body, such as a finger, and specifying coordinates of the touch position has attracted attention as one of excellent interface means. Currently, touch panels of various types, such as a resistance film type or an electrostatic capacitance type, have been produced.
As one form of the electrostatic capacitance type touch panel, there is a Projected Capacitive type touch panel disclosed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 9-511086 (1997) (referred to as “JP 9-511086 (1997) W” hereinafter), Japanese Patent Application Laid-Open No. 2010-61502 (referred to as “JP 2010-61502 A” hereinafter), Japanese Patent Application Laid-Open No. 2010-97536 (referred to as “JP 2010-97536 A” hereinafter), and Japanese Patent Application Laid-Open No. 2013-80328 (referred to as “JP 2013-80328 A” hereinafter), for example. Even if a protective plate formed of a glass plate or the like with a thickness of about several millimeters is provided on a front surface side of a touch screen incorporating a touch sensor, the Projected Capacitive type touch panel is capable of detecting a touch. The touch panel has advantages in that rigidity is excellent, the touch can be detected even at the time of wearing gloves, and a life is long since a movable part does not exist, and the like.
A touch screen configuring the touch panel disclosed in JP 9-511086 (1997) W includes, as detection wirings (detection electrodes) for detecting electrostatic capacitance, a first series of conductor elements formed of a thin conductive film and a second series of conductor elements formed on the first series of conductor elements via an insulation film. There is no electrical contact between the respective conductor elements, and a plurality of intersection points are formed. In the touch panel of JP 9-511086 (1997) W, coordinates of a position touched by a pointing body, such as a finger, is specified by detecting the electrostatic capacitance formed between the pointing body and the conductor elements. Further, the touch position between the conductor elements can be compensated using a relative value of capacitance detected by the one or more conductor elements.
In a touch screen configuring a touch panel disclosed in JP 2010-61502 A, each detection column wiring extending in a column direction is formed of a metal wiring in a zigzag pattern having inclined portions inclined at 45° with respect to a column direction, and each detection row wiring extending in a row direction is formed of a metal wiring in a zigzag pattern having inclined portions inclined at 45° with respect to a row direction. According to the touch screen in JP 2010-61502 A, a wiring density is increased without increasing parasitic capacitance between the detection wirings, and detection sensitivity of a touch can be improved.
As in the touch screen in JP 2010-61502 A, a touch screen configuring a touch panel disclosed in JP 2010-97536 A includes detection column wirings and detection row wirings formed in zigzag patterns, and is further configured by providing an isolated wiring electrically insulated from the detection column wirings and the detection row wirings in a region enclosed thereby.
A touch screen configuring a touch panel disclosed in JP 2013-80328 A has a configuration in which a region where a bundle of wirings in a column direction, which is a bundle of a plurality of detection column wirings, and a bundle of wirings in a row direction, which is a bundle of a plurality of detection row wirings, intersect with each other is divided into a block region (column wiring block region) arranged only with the detection column wirings and a block region (row wiring block region) arranged only with the detection row wirings. According to this configuration, since an area where the detection column wirings and the detection row wirings overlap is made small and parasitic capacitance (inter-wiring capacitance) formed between the detection column wirings and the detection row wirings is reduced, detection sensitivity of a touch can be enhanced. Further, even in the case where the detection column wirings and the detection row wirings are formed of an opaque highly conductive material, transmittance of display light incident on the touch screen from a display panel can be made uniform, and occurrence of moire fringes on the screen of the touch panel can be suppressed.
In each touch screen in JP 2010-61502 A and JP 2013-80328 A, the region where the bundle of wirings in the column direction and the bundle of wirings in the row direction intersect with each other is divided into the column wiring block region and the row wiring block region, and the column wiring block region and the row wiring block region are alternately arranged in the column direction and the row direction, thereby forming a checker pattern. In other words, the column wiring block regions and the row wiring block regions are respectively arranged in a staggered manner.
Since the detection column wirings and the detection row wirings are formed on mutually different wiring layers, for example, when there is a difference between a width of the detection column wiring and a width of the detection row wiring, a difference may be generated in the transmittance of the display light, reflectance of external light, and further, wavelength spectrums of transmitted light and reflected light. As a result, JP 2013-80328 A proposes that by replacing a part of the detection column wirings in the column wiring block region with floating wirings on the same layer as the detection row wirings, and further, by replacing a part of the detection row wirings in the row wiring block region with floating wirings on the same layer as the detection column wirings, a repetition frequency (number of repetitions) of a pattern is set high, thereby making it difficult to visually recognize moire fringes.
However, in the case where the column wiring block regions are arranged in the staggered manner, in order to electrically connect the detection column wirings in the column wiring block regions adjacent to each other in a diagonal direction, it is necessary to arrange the detection column wirings at four corners of each column wiring block region instead of the floating wirings. Likewise, in the case where the row wiring block regions are arranged in the staggered manner, in order to electrically connect the detection row wirings in the row wiring block regions adjacent to each other in a diagonal direction, it is necessary to arrange the detection row wirings at four corners of each row wiring block region instead of the floating wirings.
For example, when a pitch of a repetition pattern by the detection column wirings and the floating wirings in the column wiring block region is P, in order to arrange the detection column wirings at the four corners of the column wiring block region, a width of the column wiring block region needs to be P/2×(2N+1) (N is an integer). Likewise, when a pitch of a repetition pattern by the detection row wirings and the floating wirings in the row wiring block region is P, in order to arrange the detection row wirings at the four corners of the row wiring block region, a width of the row wiring block region needs to be P/2×(2N+1). As a result, a width of the bundle of wirings in the column direction and a width of the bundle of wirings in the row direction can be designed only at discrete values based on the pitch P of the repetition pattern, and these widths cannot be determined freely.
Therefore, in the touch screen having the column wiring block regions and the row wiring block regions forming the checker pattern, a size of a detection region (sensor region) of a touch cannot be determined freely, and it is difficult to adjust the size of the sensor region of the touch screen according to a screen size of the display panel.